Re: Hydrogen damage analysis

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Re: Hydrogen damage analysis
Posted by: Andy Cunningham (PID_533), E-mail: andyshome8@hotmail.com, on April 11, 2000 at 23:30 :
In Reply to: Hydrogen damage analysis posted by : Raúl Navarrete on April 05, 2000 at 19:32:
dear raul
so you have hic problems in south america! and want to find the easiest way
of recognizing and sizing.
first i'll start with the pipe.
as the pipe is extruded or rolled. the outer surfaces have a work hardened
skin and gets progressively softer towards the center. impurities migrate
towards the middle in the forming process.

second hydrogen
hydrogen will pass through the pipe wall to atmosphere unless it is
obstructed by any impurities. in this area the gas will gather and may start
to split the pipe in a laminar direction. (hic)

in service
as the pressure and temperature increases the probalbility of hic increases.
inversely the lower temp and pressure the less likelihood of hic, but the
problem never goes away 100%.

as a gas under pressure it will take the path of least resistance. in a
perfect world if the pipe wall has no impurities or internal corrosion it
will dissipate evenly around the pipe and less likely to cause a problem,
but in the real world liquid runs along the bottom of the pipe eating away
at the hardened surface leaving an easy path for the hydrogen.

scanning
0 degree 4 or 5 MHz start the scan at the bottom quarter of the pipe.
hic will starts to show in the first third from the interior surface, it is
not possible to call "hic" or "inclusion" when it is an isolated reflector.
(normal inclusions are at half wall)
hic is found at multiple depths . scan with 70 half skip 1.5mm sdh fsh. if
the the hic has started to step (crack vertically)it will show as corner
reflectors mid wall.
all the best
andy cunningham
-----------
: Dear Forum:
:
: I am working on ultrasonic spectral analysis for the detection of hydrogen damages (HIC and/or SOHIC) and I haven´t found too much literatura on this subject. Can somebody help me giving me names or leads of literature on this issue? Also, if someone has some experience, I would appreciate any comment or suggestion on how to help me with this.
:
: Thanks in advance
:
: Eng. Raúl Navarrete
: Universidad Central de Venezuela.
: Advanced ultrasonics technics laboratory
: Venezuela.

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Re: Hydrogen damage analysis R.Ramasubramanian 13:45 7/24/2000 (0)

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: dear raul : so you have hic problems in south america! and want to find the easiest way : of recognizing and sizing. : first i'll start with the pipe. : as the pipe is extruded or rolled. the outer surfaces have a work hardened : skin and gets progressively softer towards the center. impurities migrate : towards the middle in the forming process. : : second hydrogen : hydrogen will pass through the pipe wall to atmosphere unless it is : obstructed by any impurities. in this area the gas will gather and may start : to split the pipe in a laminar direction. (hic) : : in service : as the pressure and temperature increases the probalbility of hic increases. : inversely the lower temp and pressure the less likelihood of hic, but the : problem never goes away 100%. : : as a gas under pressure it will take the path of least resistance. in a : perfect world if the pipe wall has no impurities or internal corrosion it : will dissipate evenly around the pipe and less likely to cause a problem, : but in the real world liquid runs along the bottom of the pipe eating away : at the hardened surface leaving an easy path for the hydrogen. : : scanning : 0 degree 4 or 5 MHz start the scan at the bottom quarter of the pipe. : hic will starts to show in the first third from the interior surface, it is : not possible to call "hic" or "inclusion" when it is an isolated reflector. : (normal inclusions are at half wall) : hic is found at multiple depths . scan with 70 half skip 1.5mm sdh fsh. if : the the hic has started to step (crack vertically)it will show as corner : reflectors mid wall. : all the best : andy cunningham : ----------- : : Dear Forum: : : : : I am working on ultrasonic spectral analysis for the detection of hydrogen damages (HIC and/or SOHIC) and I haven´t found too much literatura on this subject. Can somebody help me giving me names or leads of literature on this issue? Also, if someone has some experience, I would appreciate any comment or suggestion on how to help me with this. : : : : Thanks in advance : : : : Eng. Raúl Navarrete : : Universidad Central de Venezuela. : : Advanced ultrasonics technics laboratory : : Venezuela.

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